The fulness of God's joy comes through obedience

Scripture references

John 15:11 (ASV)

11These things have I spoken unto you, that my joy may be in you, and that your joy may be made full.

Galatians 5:22 (ASV)

22But the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness,

Philippians 4:4 (ASV)

4Rejoice in the Lord always: again I will say, Rejoice.

Hebrews 12:2 (ASV)

2looking unto Jesus the author and perfecter of our faith, who for the joy that was set before him endured the cross, despising shame, and hath sat down at the right hand of the throne of God.

Stories

Hudson Taylor found great freedom and lightness of heart once he obeyed the words of Jesus to give to him who asks. At first, out of fear for his own needs, he resisted giving. But once he obeyed, he said that “the joy all came back in full flood tide to my heart.”
A poor table-boy who had just given his life to Christ realized that although he had nothing to give the Lord, he could give up smoking tobacco and spare the money to give Him. This decision brought him such joy, he could scarcely contain himself, and this testimony moved his master to tears.
A Christian lady takes her wealthy friend to visit an old bed-ridden saint living in a dirty and dark garret. Despite the unpleasant surroundings, the saint remains cheerful and reminds them that "it's better higher up," teaching us to look beyond our present circumstances and towards the joy that awaits us in heaven.